Swimming flipper



Feb. 7, 1967 L. FERRARO SWIMMING FLIPPER 5 Sheets-Sheet 1 Filed Nov. 30,1964 Feb. 7, 1 967 FERRARQ 3,302,222

SWIMMING FLIPPER 5 Sheets-Sheet 2 Filed NOV. 30, 1964 Feb; 7, 1967 L.FERRARO 3,302,222

SWIMMING FLIPPER i Filed Nov. 30, 1964 Y 5 Sheets-Sheet 5 United StatesPatent 3,302,222 SWIMMING FLIPPER Luigi Ferraro, 4 Via Rimana, Genoa,Italy Filed Nov. 30, 1964, Ser. No. 414,635 Claims priority, applicationItaly Dec. 5, 1963, 25,248/ 63; Feb. 28, 1964, 4,659/64; Apr. 15, 1964,8,721/ 64 11 Claims. (Cl. 9-309) The present invention relates to aswimming flipper having a propulsion surface and a shoe portion whichare made from different materials. With this arrangement, it becomespossible to select for these two parts of the flipper those materialswhich are most suitable for the different functions to be fulfilled byeach part.

It is known that flippers of the type comprising a shoe portion as inthe present invention involve different requirements in respect of thepropulsion surface or the flipper proper and of the shoe portion, theserequirements resulting from the difference in the functions of theseparts.

Wit-h regard to the shoe portion it is necessary, in fact, that thispart should have a certain flexibility and pliability in order that itmay adapt itself closely to the shape of the foot, may not pinch orfatigue the foot, thus impeding the mobility of the wearer, and that itmay not exert any kind of abrasive friction on the foot itself, thisbeing something which readily takes place in the event of pro longed useof such flippers.

On the other hand, the best natatory effect is achieved with the flipperwhen the propulsion surface exhibits a degree of sinewousness andspringiness which it is impossible to obtain with a material which issuitable for the shoe portion, in view of the fact that the qualitiesrequired in each case are almost opposite qualities. This quality ofsinewousness and springiness means that if the propulsion surface isbent and then released it returns to its initial shape rapidly andwithout substantial residual deformation.

These contrary requirements are difficult to satisfy with standardflippers, even if they are made from qualities of rubber of differingdegrees of hardnes and if the propulsion surface is subsequently givengreater rigidity with the aid of thick ribs made from the same material.tion would involve the .serious disadvantage that it would make theflipper extremely heavy, with thicknesses and profiles which aredetrimental to the propulsion effect and which, in the long run, wouldfatigue the wearer more than necessary. Consequently, the solutitonachieved would not be entirely satisfatcory from the hydrodynamicviewpoint and consequently from the view-point of how to achieve thegreatest efficiency with the least effort.

This problem is still greater with flippers of the socalled floatingtype, i.e. those made from materials of cellular structure having aspecific weight which is less than that of water and which areconsequently still more flexible than materials which do not float.

This problem and other problems in known flippers are solved inaccordance with the present invention which provides a swimming flipperhaving a propulsion surface portion and a shoe portion manufactured fromdifferent materials, wherein connection between the said two por- Thissoluice seating or socket, the shoe part being provided withcomplementary assembly members. It is generally preferable, however,that the elongated finger elements should be in one piece with thepropulsion surface and that the seatings or sockets should form a partof the shoe portion.

This type of. assembly has the additional advantage that it is possibleto make the width of the propulsion surface small in the vicinity of theshoe portion; this width may even be less than the maximum width of theshoe. In this way, the area of the said surface is diminished in theportion thereof which is nearest to the foot, this being the portionwhich provides the smallest degree of propulsion for equal fatigue inthe diver.

Further features and advantages of the flipper of the invention will bedisclosed in the detailed description thereof which is given hereinbelowwith reference to the accompanying drawings showing a plurality ofembodiments given by way of non-limitative example of the invention. Inthe drawings,

FIGURE 1 is a plan view of a flipper having a shoe portion embodying theinvention,

FIGURE 2 is a corresponding view from below,

FIGURE 3 is a view in section through thte same flipper taken along theline IIIII-I of FIGURE 2,

FIGURE 4 is a side view of the flipper of FIGURES to 3,

FIGURE 5 is a view in section along an extension of the line VV ofFIGURE 2,

FIGURE 6 is a view in section along the line VIVI of FIGURE 1,

FIGURE 7 is a plan view of a further flipper having a shoe portion andembodying the invention,

FIGURE 8 is a view from below of the flipper shown in FIGURE 7,

FIGURE 9 is a side view of the flipper shown in FIG- URES 7 and 8,

FIGURE 10 is a sectional view of the same flipper taken along the lineXX of FIGURE '8, and

FIGURES 11 and 12 are part-plan views of two other flippers embodyingthe invention.

Referring now to the drawings, a flipper 1 shown in FIGURES l to 6comprises a shoe portion 2 and a propulsion surface portion 3, joined ina manner hereinafter described.

The shoe portion 2 is made of a suitably flexible material such as, .forexample, rubber, an elastomeric substance or a flexible plasticsmaterial whereas the propulsion surface 3 is made of a less flexiblespringy thin material such as a suitable plastics material, for example,polypropylene or from metallic sheet. The propulsion surface portioncould also be made from a flexible material reinforced by metalelements. The propulsion surface 3 has (see FIGURES 1 and 4) at the endthereof adjoining the shoe portion two longitudinal lateralpr-olo-ngations having the form of elongated elements or fingers 4transversely interconnected by means of a closed annular element 5.Alternatively the element 5 could be open at the top. A small lug 6=connects the lower portion of the annular element 5 to the propulsionsurface 3; thus there is formed on the end of the propulsion surfaceadjoining the shoe portion a cage-like seating for the toe of the shoeportion, the said cage being provided with later-a1 engagement fingers4.

The shoe portion 2 is provided with lateral seatings or sockets 7 forreceiving the fingers 4, and has at the toe a transverse bulge orenlargement 8 which is integral with or attached to said shoe portionand on the sole portion has two further corresponding sector-shapedbulges 9.

In order to secure the propulsion surface to the shoe portion, thefollowing procedure is adopted:

The toe of the shoe portion 2 is inserted in the cagelike seatingprovided on the rear end of the propulsion surface 3 by the elongatedfinger elements 4, the annular or part-annular element and the lug 6,the fingers 4 being inserted in the lateral seatings '7 in the shoeportion until the upper portion of the element 5 has passed beyond thebulge 8. The bulges 9 are then introduced into the empty spaces betweenthe 'rear edge of the propulsion surface, the lower portion of theelement 5 and the lug 6. The bulge 8 and the bulges 9 then prevent anyundesired separation of the propulsion surface from the shoe portion.

The propulsion surface and the shoe portion may also be secured togetherby further engaging means (not shown) the engagement being maintained,for example, with the aid of small bars inserted one within the other.

Due to the interaction of each seating 7 and finger 4 inserted therein,the propulsion surface is fixed on the shoe portion in such manner as toprevent undesirable reciprocal oscillation of the two parts, since suchoscillation could be detrimental to the propulsive efiiciency of theflipper. The annular element '5 surrounds the shoe portion 2 in acomparatively small region around the instep or metatarsus of the foot;thus, the movement of the foot is transmitted to the propulsion surfacewithout subjecting the ankle to excessive stressing, since this point ofsecuring to the foot is nearer to the ankle than in other types offlipper. The lug 6 provides a firm bearing surface for the toe of theshoe and contributes to improved transmission of the propulsive force.

As will be seen still more clearly in FIGURES l, 3 and 6, the thicknessof the propulsion surface is slight and for the greater part constantand the said propulsion surface is provided at its end with direction orstabilization ribs 10 preventing possible lateral slipping movements ofthe propulsion surface under the force exerted. The said ribs extendtowards the shoe portion over a certain distance but stop in the zone offlexion of the propulsion surface.

Naturally, whereas the flipper described and illustrated is of the typewherein the propulsion surface may be secured by engagement and alsowithdrawn from the shoe portion, it is possible to make provision forpermanent securing of the shoe portion to the propulsion surface, forexample, by pressing or by some other suitable means.

The flipper shown in FIGURES 7 to 10 has certain advantages relativelyto that described hereinabove. The quantity of material used for thepropulsion surface is smaller; the profile and orientation of thepropulsion surface are improved, thus improving the hydrodynamicpropulsion efliciency; due to a number of modifications in theattachment of the propulsion surface to the shoe portion, the force ofthe propulsion surface is shifted into a zone nearer the ankle, so thatthe joints and muscles of the lower limbs of the swimmer, and inparticular those of the foot, are subjected (with output remainingconstant) to substantially less stress. Thus, for an equal effort, theoutput which can be achieved is substantially higher. This effort ismore rationally applied and distributed. In fact, the bearing of thepropulsion surface on the shoe portion is then limited to a simple lowercrossmember, with exclusion of collars or special complete ringssurrounding the front portion of the shoe portion. In this manner, thetoe of the shoe portion and consequently of the foot of the user bearfirmly on the rear end or neck of the propulsion surface proper duringthe active phase of the swimming movement during which this support isnecessary; the force resulting therefrom is better supported by theankle and the latter is entirely free during the return phase, so thatthe entire force of the propulsion surface is necessarily applied on theshoe portion at the point at which the rubber seatings for the ribs onthe propulsion surface commence, and, consequently, in a Zone which ismuch nearer the ankle than in all other types of flippers, with anoteworthy diminution in the stress on the joint and on the muscles.

The flipper 11 shown in FIGURES 7 to 10 comprises a portion 2 serving asa shoe and a portion 3 serving as a propulsion surface. The propulsionsurface 3 comprises two prolongations or longitudinal and lateral fingerelements 4 directed towards the rear and extending from the rear end orneck of the propulsion surface towards the shoe portion. Beyond thelower portion or sole of the shoe portion 2 the fingers 4 aretransversely interconnected by a cross-member 15, whereas no connectingelement is provided between the said fingers above the upper portion orridge of the shoe portion. A member 16 connects the cross-member 15 tothe propulsion surface 3 practically along the longitudinal median axisof the shoe portion, so that it forms, on the end of the propulsionsurface intended to be engaged in the shoe portion, a sort of frameworkfor supporting the shoe portion, corresponding practically speaking toan extension of the lateral engagement fingers 4.

The shoe portion 2 is manufactured from rubber or from a suitablepliable plastics material; it is provided with a pair of lateralseatings or sockets 7. The sockets are horizontally disposed and openout at the front of the shoe portion opposite the fingers 4, in suchmanner that the said fingers are able to penetrate into the respectivesockets with a slight degree of force, so as to provide between thepropulsion surface and the shoe portion an engagement connection capableof effectively resisting the stresses and bending forces to which theflipper is subject-ed, notably during the active phase of the swimmingmovement. It will be noted, in particular, that the sockets 7 aredisposed symmetrically but in a position withdrawn from the toe of theshoe portion. More precisely, the opening in the sockets 7 towards thepropulsion surface is disposed practically opposite the metatarsus.Furthermore, since no connecting element is provided between the fingers4 on the upper portion or ridge of the shoe portion, the swimmingmovement force is, when the swimmer displaces his leg in the directionof the under portion of his foot, supported solely by the zone ofengagement between the fingers 4 and the socket 7, and since the saidsockets are withdrawn relatively to the toe of the shoe portion, thisforce is applied to the feet at points which are nearer the ankle, insuch manner that the said joints, the muscles of the foot and moregenerally of the leg of the swimmer are stressed to a very much lesserdegree. On the other hand, in conventional swimming flippers wherein thepropulsion surface and the shoe portion are made in a single piece orare rigidly secured, the force is exerted in a zone nearer the toe ofthe foot, i.e. in a zone which is further from the ankle, so that theankle is stressed very much more considerably.

It will also be noted that, whereas there is no connection between thepropulsion surface and the shoe portion starting from the upper portionor ridge of the shoe portion, the said shoe portion bears firmly on thepropulsion surface via the lower cross-member 15 and the connectingmember 16. Consequently, during the active phase of the swimmingmovement, during which the toe of the foot is required to bear on thepropulsion surface, no lack of strength or resistance is permittedbetween the propulsion surface and the shoe portion. During the passivephase, on the contrary, i.e. during the return phase of the swimmingmovement, during which the propulsion surface bends reaiwardly and wouldrequire the excessive extension of the foot and excessive work of theankle, the toe of the shoe portion and consequently the front portion ofthe foot are not affected by the movement and it is precisely for thisreason that they are detached from each other with all the consequentadvantages in respect of efliciency and stressing, since the workingpoint is not the toe of the foot but the metatarsus.

Since the force of the propulsion surface is now transmitted entirely tothe shoe portion via the engagement sockets 7, the front zone or ridge 8of the shoe portion is preferably suitably reinforced, for example bythickening the portion of the shoe in the zone and/ or by making thiszone of a harder rubber.

The finger elements 4 and the engagement sockets 7 constitute theengagement elements operating by flexion or engagement of the flipperand have the task of withstanding and transmitting the swimming movementforce between the propulsion surface and the shoe portion. In order toprevent spontaneous or accidental detachment of the propulsion surfacefrom the shoe portion during swimming, there are longitudinal connectingelements comprising relief portions 19 projecting preferablysymmetrically on the base of the sole of the shoe portion, near the toeof the latter; when the fingers 4 have been embedded for as far as theywill go in the respective sockets 7, the cross-member 15 and the member16 are then engaged by the relief portions 19, in such manner that thepropulsion surface cannot be displaced relatively to the shoe portioneither forwardly or laterally.

FIGURES 9 and 10 show clearly that the propulsion surface is of smallthickness and preferably becomes gradually thinner towards theextremity, where it is provided with 'a series of parallel stabilisingribs 10 for preventing possible lateral slipping movements of thepropulsion surface under the force exerted. The said ribs extend towardsthe rear, i.e. towards the shoe portion, over a predeteremined length,but they are limited by the flexion zone of the propulsion surface.

The profile of the propulsion surface is of the type of a flipper havinga connecting zone 18 between the propulsion surface proper and theengagement fingers 4, so that the flexible portion of the propulsionsurface extends from the extremity of the latter (i.e. to the right inthe figures) as far as the line I-I of FIGURE 7 and the less flexible orpractically rigid portions of the propulsion surface are reduced to aminimum and are practically speaking limited solely to the zone ofattack or to the root of the engagement fingers. Furthermore, the planeof the propulsion surface has been so designed that it is slightlyinclined downwardly relatively to the engagement fingers and preferablyat an angle of 12 to 18 thereto. This feature of the propulsion surface,combined with the advantages resulting from the connection describedhereinabove operating by engagement between a flexible, springypropulsion surface arranged at an appropriate angle on the one hand anda pliable and flexible shoe portion on the other hand permits theconstruction of a type of flipper which is extremely light andfunctional and which combines the velocity effect due to the sine'wy andspringy propulsion surface with the advantages of minimum musculareffort in the swimmer.

The flippers illustrated in FIGURES 11 and 12 each comprise a lockingsystem wherein one or more retaining elements provided at any desiredappropriate point on the propulsion surface or the shoe portionco-operate with corresponding retaining elements on the shoe portion oron the propulsion surface for locking the propulsion surface and theshoe portion reciprocally in an assembly position; this locking excludespractically speaking any possibility of accidental sliding of thepropulsion surface when the swimmers foot is disposed in the shoeportion, whereas it permits the rapid withdrawal of the propulsionsurface from the shoe portion, without the aid of a tool, when thelatter is not on the foot. Thus, the double advantages aresimultaneously achieved that it is no longer possible for the propulsionsurface to be accidentally detached from the shoe portion duringswimming and that due to the possibility for rapid detachment of thepropulsion surface, it becomes possible rapidly to convert the swimmingflipper to a simple shoe which may serve for example quite easily forwalking on a beach or for climbing to safety on a rock.

The flipper 21 illustrated in FIGURE 11 comprises a shoe portion 2 and apropulsion surface 3. The propulsion surface 3 has two prolongations orlongitudinal and lateral finger elements 24- projecting to the rear ofthe neck of the propulsion surface towards the shoe portion. At theheight of the front portion of the sole of the shoe portion 2, thefinger elements 24 are transversely interconnected by a member 25 havinga solid portion which constitutes a rear prolongation of the propulsionsurface 3; the said solid portion is in FIGURE 11 concealed by the frontof the shoe portion. No connection is provided between these fingerelements above the shoe portion.

The shoe portion 2, which is made of rubber or of an appropriateplastics material having a different degree of hardness is provided witha pair of seatings or lateral sockets 27. The sockets 27 are disposedlongitudinally on the shoe portion and are open at their two ends. Thesockets 27 are slightly shorter than the finger elements 24, so thatwhen the propulsion surface is engaged in the shoe portion the fingerelements 24 penetrate as far as possible into the sockets 27 throughtheir front aperture and finally extend slightly beyond the open rearsocket ends. In the portion of each finger element 24 which thusprojects there is an aperture 401 in which engages a button orcorresponding relief portion 201 which projects externally laterally ofthe shoe portion 2. Due to the flexibility of the finger elements 24 andthe flexibility of the material from which the shoe portion is made, thebuttons 201 may be readily engaged in and withdrawn from the apertures401. Thus, for example, in order to withdraw a button 201 from theassociated aperture 401 when the shoe portion is not on the foot, itwill suffice to fold slightly towards the exterior the portion of theflexible finger element which projects or to urge towards the interiorthe, wall of the shoe portion in the vicinity o fthe button until thelatter withdraws from the aperture under the effect of the deformationof the shoe portion. On the contrary, when the shoe portion is on thefoot, this deformation is no longer possible due to the pressure of thefoot on the shoe portion, so that it is impossible for the propulsionsurface to become ac cidentally detached from the shoe portion duringswimmmg.

In the case of the flipper illustrated in FIGURE 12, the sockets 27 arealso open at the rear ends, but the portion of the finger elements 24projecting beyond the rear open socket ends when the propulsion surfaceis embedded in the shoe portion are each provided with a small tooth 402which engages over a stop member or shoulder 202 which may take the formof a relief member on the shoe portion. Alternatively the stop membersor shoulders 202 may be formed by the ends of sockets 27 in caseswherein the latter, for example in order to make the arrangement morerobust, are designed as separate elements without requiring the directcooperation of the wall of the shoe portion in order to form thesockets. The small teeth 402 are relatively short. On the other hand,the sockets 27, as already stated, are slightly deformable (i.e.preferably made from the same material as the shoe portion), so that thefinger elements 24 are readily able to pass through the sockets 27. Whenthe propulsion surface is engaged or urged as far as possible into theshoe portion, the teeth 402 emerge from the open rear ends of thesockets 27 and engage automatically in the corresponding relief portions202 which are fast with the shoe portion. In this case also, despite theflexibility of the finger element 24 and that of the shoe portion 2,when the latter is drawn on to the foot, the wall of the shoe portion isurged towards the exterior under the effect of the pressure of the foot,so that the relief portions 202 firmly retain the teeth 402. Accident-aldetachment of the propulsion surface from the shoe portion, for exampleduring swimming is thus practically impossible. In order to detach thepropulsion surface from the shoe portion when the latter is not on thefoot, the procedure will be in accordance with the indications givenwith reference to FIGURE 11, i.e. the wall of the shoe portion is urgedtowards the interior near the relief portions 202, so as to disengagethe teeth 402 from the said relief portions under the action of thedeformation of the shoe portion due to this pressure.

The embodiments described hereinabove may be modified without exceedingthe scope of the present invention. The members contributing to thelockingefi'ect, for example the buttons 201 and the apertures 401, orthe relief portions 202 and the teeth 402 may be provided in any desirednumber and they can be disposed at any desired appropriate point on theshoe portion and on the propulsion surface respectively. Furthermore,the presence of such locking members does not exclude the provision ofauxiliary retaining members such as for example the cross-member 15 andthe member 16 which co-operate with relief members 19 on the sole of theshoe portion. The connection between the shoe portion and the propulsionsurface may also be made permanent or semi-permanent by local heating,sticking or in any other manner.

What I claim is:

1. A swimming flipper comprising .a shoe portion and a propulsionportion, a socket on each side of the shoe portion, a finger on eachside of the propulsion portion engaged in each of the sockets, means forretaining the fingers in the sockets, the means for retaining thefingers in the sockets comprising bulges on the upper and lower parts ofthe shoe portion forwardly of the sockets, and an annular band integralwith the propulsion portion between the bulges and sockets and inengagement with the shoe.

2. A device as defined in claim 1 in which the openings in the socketsare at the height of the metatarsus portion of the shoe.

3. A device as defined in claim 1 further including spaced ribsextending longitudinally of the propulsion portion.

4. A device as defined in claim 1 wherein the propulsion portion isplanar and is inclined relative to a central line of the fingers.

5. A swimming flipper comprising a shoe portion and a propulsionportion, a socket on each side of the shoe portion, a finger on eachside of the propulsion portion engaged in each of the sockets, means forretaining the fingers in the sockets, the means for retaining thefingers in the sockets comprising a pair of projections on the soleportion only of the shoe adjacent the toe, and a cross-member integralwith the propulsion portion and in engagement with the sole between theprojections and the sockets.

6. A device as defined in claim wherein the means '8 for retaining thefingers in the sockets comprises a projection extending laterally fromthe shoe at each side thereof and an aperture in each finger fitted overthe projection.

7. A device as defined in claim 5 wherein the means for retaining thefingers in the sockets comprises a lateral protuberance on the end ofeach finger in engagement with an end wall of the socket.

8. A device as defined in claim 1 wherein the means for retaining thefingers in the sockets comprises a projection extending laterally fromthe shoe at each side thereof and an aperture in each finger fitted overthe projection.

9. A device as defined in claim 1 wherein the means for retaining thefingers in the sockets comprises a lateral protuberance on the end ofeach finger in engagement with an end wall of the socket.

10. A swimming flipper comprising a shoe portion and a propulsionportion, socket means carried by one of said portions, finger meanscarried by the other of said portions and engaged in said socket means,means for retaining the finger means in the socket means, the means forretaining the fingers in the sockets comprising bulges on the upper andlower parts of the shoe portion forwardly of the sockets, and an annularband integral with the propulsion portion between the bulges and socketsand in engagement with the shoe.

11. A swimming flipper comprising a shoe portion and a propulsionportion, socket means carried by one of said portions, finger meanscarried by the other of said portions and engaged in said socket means,means for retaining the finger means in the socket means, the means forretaining the fingers in the sockets comprising a pair of projections onthe sole portion only of the shoe adjacent the toe, and a cross-memberintegral with the propulsion portion and in engagement with the solebetween the projections and the sockets.

References Cited by the Examiner UNITED STATES PATENTS 242,773 6/1881Hayes 9-30l 3,178,738 4/1965 La Trell 9-309 FOREIGN PATENTS 533,2409/1955 Italy. 557,786 2/1959 Italy.

MILTON BUCHLER, Primary Examiner.

ALFRED E. CORRIGAN, Examiner.

1. A SWIMMING FLIPPER COMPRISING A SHOE PORTION AND A PROPULSIONPORTION, A SOCKET ON EACH SIDE OF THE SHOE PORTION, A FINGER ON EACHSIDE OF THE PROPULSION PORTION ENGAGED IN EACH OF THE SOCKETS, MEANS FORRETAINING THE FINGERS IN THE SOCKETS, THE MEANS FOR RETAINING THEFINGERS IN THE SOCKETS COMPRISING BULGES ON THE UPPER AND LOWER PARTS OFTHE SHOE PORTION FORWARDLY OF THE SOCKETS, AND AN ANNULAR BAND INTEGRALWITH THE PROPULSION PORTION BETWEEN THE BULGES AND SOCKETS AND INENGAGEMENT WITH THE SHOE.